0.2.39: bitcoin-denominated view, first-login flow, unfunded + tax center

- BTC prices: btc_prices table, CSV upload on Import page (auto-detected
  date/close columns, upsert by date), entities.close_date as the BTC entry
  mark; statements carry btc_price_cents (as-of) + btc_close_price_cents.
  LP capital blocks show paid-in vs current value in bitcoin terms.
- First login: accounts on the shared default password are flagged
  (must_change_password) and blocked behind a full-screen password change;
  external accounts then get a one-time welcome tour with a 2FA offer
  (users.onboarded_at).
- LP portal: Unfunded (callable commitment) metric; Tax documents center
  aggregating K-1/tax docs across funds, grouped by year.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/ten31portal/models.py

@@ -2,10 +2,11 @@
 
 import enum
 from datetime import date, datetime
+from datetime import date as _date  # for fields literally named "date"
 from decimal import Decimal
 from typing import Optional
 
-from sqlmodel import Field, SQLModel, Column, String, JSON, UniqueConstraint
+from sqlmodel import Field, SQLModel, Column, Date, String, JSON, UniqueConstraint
 
 
 # --- Enums ---
@@ -85,6 +86,11 @@ class User(SQLModel, table=True):
     totp_enabled: bool = Field(default=False)
     # JSON list of sha256 hex digests of unused one-time recovery codes.
     totp_recovery_codes: str | None = Field(default=None)
+    # True while the account is on the shared default password — the portal forces a
+    # password change before anything else. Cleared by change-password / admin reset.
+    must_change_password: bool = Field(default=False)
+    # When the investor finished (or skipped) the first-login welcome flow. Null = show it.
+    onboarded_at: datetime | None = Field(default=None)
     created_at: datetime = Field(default_factory=datetime.utcnow)
 
 
@@ -100,9 +106,25 @@ class Entity(SQLModel, table=True):
     # For a GP/mgmt entity that is also an LP with capital accounts (e.g. Ten31 LLC), link to
     # its investor account so its Assets view can pull real per-fund balances from the eNAV.
     linked_user_id: int | None = Field(default=None, foreign_key="users.id", index=True)
+    # Final close of the fund/SPV — the BTC entry mark: paid-in capital is valued at the BTC
+    # price on this date for the bitcoin-denominated view. Null = no BTC view for this fund.
+    close_date: date | None = Field(default=None)
     created_at: datetime = Field(default_factory=datetime.utcnow)
 
 
+class BtcPrice(SQLModel, table=True):
+    """Daily (or as-uploaded) BTC/USD closing prices from the admin's CSV.
+
+    Statements are valued at the newest price on or before their as-of date, so the CSV
+    doesn't need every calendar day — quarter-end rows are enough."""
+
+    __tablename__ = "btc_prices"
+
+    id: int | None = Field(default=None, primary_key=True)
+    date: _date = Field(sa_column=Column(Date, unique=True, nullable=False))
+    price_cents: int
+
+
 class Holding(SQLModel, table=True):
     __tablename__ = "holdings"